Rotella is a brand that most auto parts have. Regular oil that has sufficient ZDDP. Not expensive at all. Many oils do not have the ZDDP that the older engines need.
Zinc dialkyl dithio phosphate (ZDDP, ZnDTP, or ZDP) is a family of zinc salts of dithio organophosphates. They are soluble in nonpolar solvents, so they easily dissolve in mineral and synthetic oils used as lubricants. They come under CAS number [68649-42-3]. In aftermarket oil additives, the percentage of ZDDP ranges approximately between 2-15%.
The alkyl groups can be branched and linear alkanes between 1-14 carbons length, 2-butyl, pentyl, hexyl, 1,3-dimethylbutyl, heptyl, octyl, isooctyl (2-ethylhexyl), 6-methylheptyl, 1-methylpropyl, dodecylphenyl, and others.
A mix of zinc dialkyl(C3-C6)dithiophosphates come under CAS number [84605-29-8]. List of other examples with their CAS numbers is here.
The main use of ZDDP is in anti-wear additives to lubricants (eg. greases, motor oils). To date it is the dominant anti-wear agent, present in most machine and motor oils in amount of about 1%. However for motor oil applications the amount of ZDDP has to be minimized, as the zinc and phosphorus emissions damage catalytic converters, .
